what factors cause the rise and fall of empires?

Question

i.e. roman empire, tang dynasty, Byzantime empire, Song etc.

Answer 1

see http://en.wikipedia.org/wiki/Human_migration or if you are looking for specific empires look at http://en.wikipedia.org/wiki/List_of_empires for the particular empire or empires you are interested in.

Good Luck!!!

Answer 2

For lands around the world that have been developed by conquest and colonization, the common pattern is that the ruling country exploits the masses for the benefit of themselves as owners. This system cannot sustain because the oppressed masses eventually develop, organize, and rebel against the controlling forces. So the state loses stability when it is based on such an unfair imbalance of power and resources.

When those in power write, interpret or execute the laws to benefit themselves and their private interests instead of sustaining the greater good of the state, this leads to corruption that either bankrupts the system or creates war between oppressed masses who then fight for independence and break off or take over. Then the cycle starts again. The recurring problem is that when the system run by a few leaders to govern the masses no longer represents the developing population, it becomes bureaucratic or corrupted. The solution is to work toward localized government to maintain a healthy system of checks and balances, sustainable growth and development, and as direct representation as possible.

In the meantime, countries have historically developed through colonization under top-down government until local populations are educated enough to operate independently. So we continue to see this pattern of development until all populations achieve localized governments and economies without dependence on, or oppression by, foreign jurisdiction.